This invention relates to 2,4-diaminopyrimidines and their use as sensitizers of tumor cells to anticancer agents.
In cancer chemotherapy the effectiveness of anticancer drugs is often limited by the resistance of tumor cells. Some tumors such as of the colon, pancreas, kidney and liver are generally innately resistant, and other responding tumors often develop resistance during the course of chemotherapy. The phenomena of multidrug resistance (MDR) is characterized by the tumor cell's cross-resistance to structurally unrelated drugs. The drugs which are the target of resistance include adriamycin, daunomycin, vinblastine, vincristine, actinomycin D and etoposide. The resistance cells are often associated with over-expression of the mdr1 gene. This gene product is a family of 140-220 kd trans-membrane phosphoglycoprotein (P-glycoprotein) which functions as an ATP-dependent efflux pump. Thus, it has been postulated that this efflux mechanism keeps the intracellular level of the anticancer drug low, allowing the tumor cells to survive.
In recent years various substances such as verapamil, nifedipine and diltiazem have been used in in vitro experimental systems to reverse the MDR phenomena. More recently some of these agents have been tested clinically as MDR reversing agents. Little efficacy has been observed with verapamil or trifluoroperazine. Thus, there is a need for an effective MDR reversing agent.
Fukazawa, et al. describes a series of heterocyclic compounds (EP Application No. 89310235.0) useful as anticancer-drug reinforcing agents. This same utility is also claimed for a series of pteridine derivatives (EP Application No. 89117610.9).
Tomino, et al. (EP Application No. 89313595.4) claims a series of pyrimidines, including 2,4-diaminopyrimidines, useful in the treatment of neurological diseases.
A series of 2,4,6-triaminopyrimidine-N-oxides (U.S. Pat. No. 4,945,093) are described as being useful for promoting hair growth.